Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Summon Minions:

Summons 1d6 Minions to aid in battle.

Celestial Drake (Minion):

• AC: 15, HP: 150, Speed: 30 ft., fly 60 ft.
• Attacks: Each drake can make one attack per round.
• Bite: +10 to hit, 3d8 + 5 piercing damage.
• Tail Swipe: +10 to hit, 2d6 + 5 bludgeoning damage.

Multiattack. Zyrathar makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) piercing damage.

Claw. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +14 to hit, reach 20 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons:

Solar Breath. The dragon exhales fire in an 60-foot line that is 10 feet wide. Each creature in that line must make a DC 21 Dexterity saving throw, taking 56 (16d6)radiant damage on a failed save, or half as much damage on a successful one.

Change Shape. The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the dragon's choice).

In a new form, the dragon retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The dragon regains spent legendary actions at the start of its turn.

Radiant Eruption (Costs 2 Actions): Choose a point within 120 feet, creating a 20-foot radius of radiant light. Creatures in the area must succeed a DC 24 Constitution saving throw or take 3d10 radiant damage and be blinded until the end of their next turn.

Celestial Reinforcement: Summon 1 Celestial Drakes to the battlefield.